1. Field of the Invention
The present invention relates to an apparatus for effectively removing spherical toner particles from an image bearing member, and an image forming apparatus of electrophotographic type. More particularly, it relates to an image forming apparatus including a cleaning means having an elastic blade for removing spherical toner particles in a rubbing fashion.
2. Related Background Art
In conventional image forming apparatuses of an telectrophotographic type, as a cleaning means for cleaning a photosensitive drum, a cleaning means 102 having an elastic blade 105 as shown in FIG. 14 is known. Such a cleaning means has widely been used because of simple construction and cheapness.
The cleaning means 102 comprises a waste toner container 103, a support member 104 attached to a surface of the container opposed to a photosensitive drum 101, an elastic blade 105 supported by the support member 104, and a toner collecting sheet 106 attached to the waste toner container 103 below the elastic blade 105.
The elastic blade 105 is formed from polyurethane rubber. A tip end of the elastic blade 105 is urged against a surface of the photosensitive drum 101 (rotated in a direction shown by the arrow in FIG. 14) from a direction (counter direction) opposite to the rotational direction of the photosensitive drum.
In conventional image forming apparatuses using toner manufactured by a crushing method, an urging pressure (abut pressure) of the elastic blade 105 against the photosensitive drum 101 was selected to be about 25 gxc2x7f/cm at the minimum. However, as recent color image forming apparatuses have been progressed, a non-magnetic toner manufactured by polymerization has been used as a one-component developer.
The non-magnetic toner manufactured by polymerization (i.e., polymerized toner) includes substantially spherical toner particles, and low soft substance such as wax may be added to such toner. By adding the low soft substance to the polymerized toner, oil coating in a fixing device which was conventionally effected to prevent offset can be omitted, and, even when an image is printed on an OHP sheet, oil can be prevented from adhering to the OHP sheet.
On the other hand, it is well-known that it is difficult to scrape and remove the polymerized toner from the surface of the photosensitive drum 101 by means of the elastic blade (cleaning blade) 105 of the cleaning means 102. It is considered that the reason is that the tip end of the cleaning blade 105 urged against the surface of the photosensitive drum 101 is vibrated due to the rotation of the photosensitive drum, and the polymerized toner comprising spherical toner particles is apt to pass through a small gap between the tip end of the cleaning blade and the surface of the photosensitive drum created due to such vibration.
An object of the present invention is to provide a cleaning apparatus and an image forming apparatus using such a cleaning apparatus, in which spherical toner particles such as polymerized toner can be removed from an image bearing member such as a photosensitive drum, without occurring poor cleaning.
To achieve the above object, according to the present invention relating to a cleaning apparatus to remove toner from an image bearing member for bearing a toner image, which the toner to be removed is a one-component toner having a shape coefficient SF1 of 100 to 120, and a blade-shaped elastic member rubbing a surface of the image bearing member is used for removing the toner, and the elastic member is urged against the surface of the image bearing member with line pressure of 55 to 95 gxc2x7f/cm.
Further, the present invention provides an image forming apparatus for forming a toner image on an image bearing member and for transferring the toner image onto a transfer material, comprising a toner image forming means for forming a toner image with one-component toner having a shape coefficient SF1 of 100 to 120 on the moving image bearing member, a transfer means for transferring the toner image formed on the image bearing member onto a transfer material, and a blade-shaped cleaning means disposed at a downstream side of the transfer means in a moving direction of the image bearing member to be urged against a surface of the image bearing member with a line pressure of 55 to 95 gxc2x7f/cm to scrape and remove residual toner remaining on the image bearing member after transferring.